Internal combustion engine with electric starting system

ABSTRACT

An internal combustion engine includes an engine block, an electric motor, a worm coupled to and rotated by the electric motor, a worm gear coupled to and configured to be rotated by the worm, a crankshaft configured to rotate about a crankshaft axis, a flywheel including a flywheel cup having flywheel protrusions, a clutch driven by the worm gear and configured to engage the one or more flywheel protrusions such that the crankshaft is rotated, and an energy storage device electrically coupled to the electric motor. The clutch is configured to disengage from the flywheel protrusions when the rotational speed of the crankshaft exceeds the rotational speed of the worm gear. When the electric motor is activated, the electric motor rotates the worm rotating the worm gear, which causes the clutch to engage the flywheel protrusions, transferring worm gear rotation to the flywheel and the crankshaft to rotate the engine for starting.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a U.S. National Stage Application ofPCT/US2017/029946, filed Apr. 27, 2017, which claims the benefit of andpriority to U.S. Provisional Patent Application No. 62/328,985, filedApr. 28, 2016, which is incorporated herein by reference in itsentirety.

BACKGROUND

The present invention generally relates to internal combustion enginesand outdoor power equipment powered by such engines. More specifically,the present invention relates to an electric starting system for anengine.

Outdoor power equipment includes lawn mowers, riding tractors, snowthrowers, pressure washers, portable generators, tillers, log splitters,zero-turn radius mowers, walk-behind mowers, riding mowers, industrialvehicles such as forklifts, utility vehicles, etc. Outdoor powerequipment may, for example use an internal combustion engine to drive animplement, such as a rotary blade of a lawn mower, a pump of a pressurewasher, the auger a snow thrower, the alternator of a generator, and/ora drivetrain of the outdoor power equipment.

Many pieces of outdoor power equipment include engines that are manuallystarted with a recoil starter. To start the engine, the user mustmanually pull a recoil starter rope. Other pieces of outdoor powerequipment include electric starting systems in which a starter motorpowered by a battery starts the engine. Conventional electric startingsystems typically require an engine block different than the engineblock used with a recoil starting system. The electric start engineblock adds a mounting location that the starter motor is secured to.Conventional electric starting systems also require a flywheel with aring gear that is engaged with the starter motor pinion gear.

SUMMARY

One embodiment of the invention relates to an internal combustion engineincluding an engine block, an electric motor, a worm coupled to theelectric motor and configured to be rotated by the electric motor, aworm gear coupled to the worm and configured to be rotated by the worm,a crankshaft configured to rotate about a crankshaft axis, flywheelincluding a flywheel cup having one or more flywheel protrusions, theflywheel configured to rotate about the crankshaft axis, and a clutchdriven by the worm gear. The clutch is configured to engage the one ormore flywheel protrusions such that the crankshaft is rotated about thecrankshaft axis, where the clutch is configured to disengage from theone or more flywheel protrusions when the rotational speed of thecrankshaft exceeds the rotational speed of the worm gear. The internalcombustion engine further includes an energy storage device electricallycoupled to the electric motor to power the electric motor. When theelectric motor is activated, the electric motor rotates the worm, whichin turn rotates the worm gear, which in turn causes the clutch to engagethe one or more flywheel protrusions, thereby transferring worm gearrotation to the flywheel and the crankshaft to rotate the engine forstarting.

Another embodiment of the invention relates to an electric startingsystem for an internal combustion engine including an electric motor, aworm coupled to the electric motor and configured to be rotated by theelectric motor, a worm gear coupled to the worm and configured to berotated by the worm, a flywheel including a flywheel cup having one ormore flywheel protrusions, and a clutch driven by the worm gear. Theclutch is configured to engage the one or more flywheel protrusions suchthat a crankshaft of the engine is rotated about a crankshaft axis,where the clutch is configured to disengage from the one or moreflywheel protrusions when the rotational speed of the crankshaft exceedsthe rotational speed of the worm gear. The electric starting systemfurther includes an energy storage device electrically coupled to theelectric motor to power the electric motor. When the electric motor isactivated, the electric motor rotates the worm, which in turn rotatesthe worm gear, which in turn causes the clutch to engage the one or moreflywheel protrusions, thereby transferring worm gear rotation to theflywheel and the crankshaft to rotate the engine for starting.

Alternative exemplary embodiments relate to other features andcombinations of features as may be generally recited in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingfigures, in which:

FIG. 1 is a perspective view of an internal combustion engine includingan electric starting system, according to an exemplary embodiment.

FIG. 2 is a bottom perspective view of a portion of the engine of FIG.1.

FIG. 3 is a perspective view of a portion of the engine of FIG. 1,according to an exemplary embodiment.

FIG. 4 is a perspective view the engine of FIG. 1 with the blowerhousing removed, according to an exemplary embodiment.

FIG. 5 is a perspective view of a portion of the engine of FIG. 1,according to an exemplary embodiment.

FIG. 6 is an exploded view of several components the engine of FIG. 1.

FIG. 7 is a section view of the engine of FIG. 4.

FIG. 8 is a perspective view of a portion of the engine of FIG. 1,according to an exemplary embodiment.

FIG. 9 is a perspective view of an internal combustion engine includingan electric starting system, according to an exemplary embodiment.

FIG. 10 is an exploded view of a several components of an internalcombustion engine including an electric starting system, according to anexemplary embodiment.

DETAILED DESCRIPTION

Before turning to the figures, which illustrate the exemplaryembodiments in detail, it should be understood that the presentapplication is not limited to the details or methodology set forth inthe description or illustrated in the figures. It should also beunderstood that the terminology is for the purpose of description onlyand should not be regarded as limiting.

Referring to FIGS. 1-3, an internal combustion engine 100 including anelectric starting system 110 is shown according to an exemplaryembodiment. The internal combustion engine 100 includes an engine block102 having a cylinder, a piston, and a crankshaft 104. The pistonreciprocates in the cylinder to drive the crankshaft 104. The crankshaft104 rotates about a crankshaft axis 106. A flywheel 112 (FIG. 3) isattached to the crankshaft 104. The engine 100 also includes a fuelsystem for supplying an air-fuel mixture to the cylinder (e.g., acarburetor, an electronic fuel injection system, a direct fuel injectionsystem, etc.), an air filter assembly 107, a cylinder head 109, amuffler 111, and a fuel tank 113. The engine 100 also includes a blowerhousing 105 (cowl, cover) configured to direct cooling air over theengine block 102 and other components of the engine during engineoperation. A fan (e.g., a fan driven by the crankshaft 104, an electricfan, etc.) draws cooling air from the ambient environment into theblower housing 105 through one or more air inlets 116. The fan may be acomponent of or coupled to the flywheel 112. In the illustratedembodiment, the crankshaft 104 and the crankshaft axis 106 are orientedvertically. In some embodiments, the crankshaft 104 and the crankshaftaxis 106 are oriented horizontally. In some embodiments, the engineincludes multiple cylinders, for example, a two cylinder engine arrangedin a V-twin configuration.

Referring to FIGS. 2 and 6, the electric starting system 110 includes anelectric motor 120, a transmission 130, and an energy storage devicesuch as a battery 155 (e.g., a lithium-ion battery, a capacitor,multiple batteries or capacitors, or other suitable energy storagedevices). The electric starting system 110 is located within the blowerhousing 105. The electric motor 120 is electrically coupled to thebattery 155 to be powered by the battery 155. In one embodiment, theelectric motor 120 is a 12 volt (V) electric motor. In anotherembodiment, the electric motor 120 is a 7.2 V electric motor. In otherembodiments, the electric motor 120 may be otherwise rated. The battery155 may include one or more battery cells (e.g., lithium-ion cells). Insome embodiments, the battery 155 may be further configured to powerother systems of the engine 100, such as an electronic control havingcontrol circuitry coupled to sensors or detectors integrated with theengine 100 (e.g., brake release, fuel-level detector, ignition-foulingdetector, governor, vacuum sensors, pressure sensors, temperaturesensors, etc.). When activated in a response to a user input (e.g., viaa key switch, a push button, a bail start system, a trigger start systemfor a pressure washer, other automatic start system, etc.), the electricstarting system 110 rotates the crankshaft 104 to enable starting of theengine 100.

The transmission 130 includes a worm 135 coupled to the electric motor120, a worm gear 140 engaged with the worm 135, a clutch 108, and aflywheel 112 including a flywheel cup 115. Referring to FIG. 3, theflywheel 112 is attached to the crankshaft 104 and includes a flywheelcup 115 with one or more flywheel protrusions 117. The flywheel cup 115rotates with the flywheel 112. As such, the flywheel cup 115 andflywheel protrusions 117 rotate with the rotation of the crankshaft 104about a crankshaft axis 106 upon rotation (e.g., cranking) of the engine100. In some other embodiments, the flywheel 112 includes flywheelprotrusions attached directly thereto without including the flywheel cupdescribed above.

The electric motor 120 is fastened to a mounting bracket 125 (e.g., byscrews, bolts, rivets, or other appropriate fasteners). The underside124 of the blower housing 105 includes an outer or boundary portion 126defined by one or more sidewalls 127. The electric motor 120 ispositioned within a recess 128 formed in the underside 124 of the blowerhousing 105. A mounting plate 129 is fastened to the underside 124 ofthe blower housing 105 (e.g., by screws, bolts, rivets, or otherappropriate fasteners) to hold the battery 155. The mounting plate 129includes a cutout 131 that accommodates the electric motor 120. One endof the worm 135 is coupled to the electric motor's output shaft 121 androtates about a worm axis 122. The opposite end of the worm 135 issupported by a bearing 123. The bearing 123 is attached to or acomponent of the blower housing 105 and is located on the underside 124of the blower housing 105. The battery 155 is located between the blowerhousing 105 and the mounting plate 129. In some embodiments, the battery155 is fastened to the underside 124 of the blower housing (e.g., byscrews, bolts, rivets, or other appropriate fasteners). In someembodiments, the battery 155 is fastened to the mounting plate 129(e.g., by screws, bolts, rivets, or other appropriate fasteners). Inother embodiments, the battery 155 is positioned on the topside of theblower housing 105 (shown in FIG. 9).

As shown in FIGS. 4-5, in some embodiments, a mounting frame 145 isfastened to a portion of the engine 100 (e.g., blower scroll 152) viaapertures 147 (e.g., by screws, bolts, rivets, or other appropriatefasteners). The mounting frame 145 includes a center portion 151 withone or more legs 149 branching therefrom. The center portion 151includes an aperture 148 within which the worm gear 140 is positioned.The mounting frame 145 further includes a cutout 144 that accommodatesthe worm gear 140 and electric motor 120. As discussed above, one end ofthe worm 135 is coupled to the electric motor's output shaft 121 androtates about a worm axis 122. The opposite end of the worm 135 issupported by a bearing 123. The bearing 123 is attached to or acomponent of the mounting frame 145. As shown in FIG. 4, in somearrangements, a cover 153 may be fastened onto the mounting frame 145 tohouse the worm gear 140 and worm 135. The blower housing 105 can bemounted onto the engine 100 on top of and covering the mounting frame145. Accordingly, supporting the worm gear 140, worm 135, and electricmotor 120 on the mounting frame 145 and not on the blower housing 105allows an operator and/or an original equipment manufacturer (OEM) toreadily exchange blower housings (e.g., to differently accessorize,customize) for different customers.

The worm gear 140 is configured to rotate about the crankshaft axis 106and selectively drive the crankshaft 104 via the clutch 108 (e.g., astarter clutch, a freewheeling clutch, an overrunning clutch, andoverspeed clutch, etc.). The clutch 108 is coupled to worm gear 140.When the clutch 108 is engaged (in an engaged position) the worm gear140 and the crankshaft 104 rotate together. When the clutch 108 isdisengaged (in a disengaged position) the worm gear 140 and thecrankshaft 104 are free to rotate independently of one another. Thecrankshaft axis 106 is perpendicular to the worm axis 122. In otherembodiments, the worm axis 122 is otherwise angled relative to thecrankshaft axis 106.

When cranking (e.g., a starting operation) is initiated by the user, theclutch 108 is engaged so that the worm gear 140 drives the crankshaft104. Once the engine 100 has started, the clutch 108 disengages when thecrankshaft 104 begins to rotate faster than the worm gear 140 (anoverspeed condition), allowing the worm gear 140 to rotate independentlyof the crankshaft 104. In some embodiments, as illustrated in FIGS. 3and 7, the clutch 108 includes a pulley 136 and two dogs 137 movablerelative to the pulley 136 between an extended or engaged position(shown in FIG. 2) and a retracted or disengaged position (shown in FIG.7). The pulley 136 is coupled to and rotates with the worm gear 140.

When activated in a response to a user input, the electric startingsystem 110 rotates the crankshaft 104 to rotate (e.g., crank) the engine100. The electric motor 120 rotates the worm 135. The worm 135 iscoupled to the worm gear 140 and rotates the worm gear 140. The clutch108 is engaged so the dogs 137 extend outward (e.g., fly out) from thecrankshaft axis 106. The dogs 137 engage with the flywheel 112 via theflywheel protrusions 117 and rotate the crankshaft 104 to rotate (e.g.,crank) the engine 100. The worm gear 140 includes one or moreprotrusions 141 (e.g., one for each dog 137) configured to limit therange of travel of the dogs 137 upon cranking of the engine 100. Whenthe crankshaft 104 begins to rotate faster than the worm gear 140 (anoverspeed condition), the dogs 137 are retracted by contact with (e.g.,pushed inward toward a retracted position by) the flywheel protrusions117. Accordingly, the worm gear 140 is then allowed to rotateindependently from the crankshaft 104. The electric motor 120 is turnedoff and rotation of the worm 135 and the worm gear 140 stops. Theelectric motor 120 may be turned off automatically in response to theengine reaching a threshold speed (e.g., as determined by monitoring theignition system or spark plug), in response to the user removing thestart input (e.g., stops turning the key switch or pushing the startbutton), after a set period of cranking time (e.g., 5 seconds), etc.Accordingly, an engine speed sensor and/or timer may be included. Theengine speed sensor determines the engine speed based off of signalsfrom the crankshaft position, ignition system, etc. The timer (e.g.,timing circuit) monitors the lapsed time from the start of enginecranking. In response to these signals, the electric motor 120 may beturned off automatically.

The worm 135 and the worm gear 140 are configured to rotate thecrankshaft 104 at a lower speed than the rotational speed of theelectric motor 120 and thereby produce higher torque at the crankshaft104 than at the electric motor 120. Compared to conventional startermotors mounted to the engine block, this permits the use of ahigher-speed, lighter, and more compact electric motor 120, while stillproducing sufficient torque at the crankshaft 104 to rotate (e.g.,crank) the engine 100. For example, the electric motor 120 may be a highspeed motor rated for operation at 12,000 revolutions per minute (rpm)and the worm 135 and worm gear 140 reduce that rotational speed by agear reduction ratio of 30:1 comparing the rotational speed of theelectric motor 120 to the rotational speed of the crankshaft 104, with aresulting rotational speed of the crankshaft 104 of approximately 400rpm. As another example, the gear reduction ratio may be 45:1, with aresulting gear speed of approximately 267 rpm. In some embodiments, thegear reduction ratio is between 30:1 and 50:1.

The engine 100 may also include a charging system to charge the battery155. In some embodiments, the charging system includes an alternator toproduce electricity. The alternator may be driven directly or indirectly(e.g., by a transmission, belt, chain, etc.) by the crankshaft 104. Inother embodiments, other types of charging systems may be used. Forexample, an ignition coil waste spark charging system may be used inwhich waste sparks from the ignition coil are harvested to providecharging energy. In some embodiments excess energy from the ignitionsystem is harvested to charge the battery 155. In a magneto or sparkignition system extra energy in the form of ignition sparks or pulsescan be harvested and stored in the battery 155. Though a spark basedignition system is discussed as an example other types of ignitionsystems are possible. The excess energy of the ignition system may alsobe sufficient to power the controller or other electrical componentsincluded in the engine. After the engine 100 is started, there is arelatively abundant amount of excess energy that can be harvested aselectricity. For example, the energy from the two positive pulses orsparks of a four-cycle magneto ignition system can yield about one ampof current. Other types of ignition systems also provide waste energythat could be harvested to power an electronic governor system. In afour-cycle magneto ignition system there is a waste spark on the exhauststroke of the cylinder. In such a system, the two positive pulses orsparks and the waste negative pulse or spark could all be harvested. Asanother example, a charge coil for a capacitor discharge ignition (CDI)system can be used as a charging system for the battery 155.

FIG. 8 illustrates a portion of electric starting system 110 accordingto an exemplary embodiment. In this embodiment, the worm gear 140includes a damper 142 that is positioned between the protrusion 141 ofthe worm gear 140 and the dog 137 of the clutch 108. The damper 142 isconfigured to soften the initial engagement of the dog 137 with theprotrusion 141 of the worm gear 140. In some embodiments, the damper 138is made of an elastomer or rubber suitable able to slightly deform todampen the initial engagement. In some embodiments, the dogs 137 aremade of an elastomer or rubber. Without the damper 142, there may be asignificant impact between the dogs and the protrusions 141, causing aloud noise (e.g., a “thud” or “clunk”) at initial engagement when thedogs 137 initially contact the protrusions 141 of the worm gear 140.This type of contact may result in wear or breakage of the worm gear140, the clutch 108, and/or the worm 135. Though only one damper 142 isillustrated a second damper is similarly positioned between theprotrusion and dog that are not shown. In some embodiments, more thantwo dampers may be included with the electric starting system 110.

In some embodiments, the electric starting system 110 further includes acontroller 143 (FIG. 6) configured to control operation of the electricstarting system 110. The controller 143 may be separate from orincorporated into a multi-purpose engine controller (e.g., an ECU). Insome embodiments, the controller 143 includes hard-wired circuitry, butnot a computer processing unit. In other embodiments, the controller 143does include a processor. In some embodiments, the controller 143 ispart of the battery 155 and is located within the battery housing. Thecontroller 143 may be configured to control operation of the electricmotor 120. For example, in addition to or in place of the dampers 142described above, the controller 143 may control the electric motor 120to perform a soft start in which the force applied during initialengagement of the dogs 137 and the protrusions is reduced by increasingthe rotational speed of the electric motor 120 over time. When theelectric motor 120 first begins to rotate it does so at a relativelyslow speed so that a relatively small force is applied during initialengagement. The controller 143 gradually increases this relatively slowspeed until the electric motor is operating at its full rated speed. Insome embodiments, the controller 143 uses pulse width modulation (e.g.,via an electronic control) to control the power supplied to the electricmotor 120 and thereby vary the rotational speed of the electric motor120.

Referring now to FIGS. 9-10, an engine 100 including an electricstarting system 110 is illustrated according to exemplary embodiments inwhich the fixed battery 155 is replaced by a removable, rechargeablebattery 655.

As illustrated in FIG. 9, the blower housing 105 includes a batteryreceiver 605 that is electrically coupled to the electric motor 120. Thebattery receiver 605 is configured to receive and secure the removablebattery 655 to the blower housing 105 and to the engine 100. The blowerhousing 105 includes an air intake 606 that includes the air inlets 116and a main body portion 607. As illustrated in FIG. 9, the batteryreceiver 605 is incorporated into the main body portion 607. Asillustrated in FIG. 10, the battery receiver 605 is incorporated intothe air intake 606. In embodiments where the battery receiver 605 isincorporated into the air intake 606, sufficient air passages areprovided in the air intake 606 such that cooling air can freely enterthe engine 100. The components shown in FIG. 10 take the place of manualstarter recoil components. The configuration of the components allowsfor easy changeover from a manual starter recoil system to an electricstarting system. For example, during changeover, the manual starter isremoved and the electric starting system 110 is assembled withoutchanging the blower housing, cylinder block, etc. In such aconfiguration, the worm 135, worm gear 140, air intake 606, clutch 608,electric motor 120, and battery 655 are part of a single assembly thatis exchangeable with a manual recoil starter system. During the assemblyprocess of the engine 100, the starter system, whether it is a manualrecoil starter system or the electric starting system 110 describedherein, is one of the last portions (or the last portion) of the engine100 to be assembled. When assembling the electric starting system 110 tothe engine 100, no components of the engine 100 need to be changed(e.g., tailored, adjusted), added, or removed to enable the use of theelectric starting system 110 in place of a manual recoil starter.

In some embodiments, the battery 655 includes slots or grips for liftingand holding the battery 655. A locking mechanism, such as a hook orlatch may snap into place when the battery 655 is inserted into thebattery receiver 605 and hold the battery 655 in the battery receiver605. Pinching the grips together may release the locking mechanism toallow removal of the battery 655 from the battery receiver 605. Theremovable battery 655 may be charged at a charging station or mayinclude a charging port integrated with the battery 155 (e.g., batterypack with charging port to receive a connection from a wire coupled toan outlet or the charging station). The battery 655, in otherembodiments, may alternatively plug directly into a wall outlet, or thecharging station may be wall mounted or plug directly into a walloutlet. Removable batteries, battery receivers, charging stations, andother features for providing electrical power to an electric motor anddetails related to internal combustion engines and electric startingsystems are described in commonly owned U.S. Pat. No. 9,127,658, whichis incorporated herein by reference in its entirety.

The construction and arrangements of the starter system for an engine,as shown in the various exemplary embodiments, are illustrative only.Although only a few embodiments have been described in detail in thisdisclosure, many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter described herein. Someelements shown as integrally formed may be constructed of multiple partsor elements, the position of elements may be reversed or otherwisevaried, and the nature or number of discrete elements or positions maybe altered or varied. The order or sequence of any process, logicalalgorithm, or method steps may be varied or re-sequenced according toalternative embodiments. Other substitutions, modifications, changes andomissions may also be made in the design, operating conditions andarrangement of the various exemplary embodiments without departing fromthe scope of the present invention.

What is claimed is:
 1. An internal combustion engine, comprising: anengine block; a blower housing configured to direct cooling air to theengine block; an electric starting system, comprising: an electricmotor; a transmission; and an energy storage device located within theblower housing, wherein the energy storage device is electricallycoupled to the electric motor to power the electric motor; a crankshaftconfigured to rotate about a crankshaft axis; wherein when the electricstarting system is activated, the electric starting system rotates thecrankshaft to rotate the engine for starting.
 2. The internal combustionengine of claim 1, wherein the electric motor and the transmission arelocated within the blower housing; wherein the electric motor is securedto an underside of the blower housing.
 3. The internal combustion engineof claim 1, further comprising: a mounting frame; wherein the electricmotor and the transmission are coupled to the mounting frame; whereinthe blower housing is configured to be interchangeable with a secondblower housing.
 4. The internal combustion engine of claim 1, furthercomprising: a controller configured to control the electric motor tostart at an initial rotational speed and increases the rotational speedover time.
 5. The internal combustion engine of claim 1, furthercomprising a mounting plate, wherein the energy storage device isfastened to the mounting plate.
 6. The internal combustion engine ofclaim 5, wherein the energy storage device is located between the blowerhousing and the mounting plate.
 7. The internal combustion engine ofclaim 1, wherein the energy storage device is fastened to an undersideof the blower housing.
 8. The internal combustion engine of claim 1,wherein the internal combustion engine further includes a chargingsystem to charge the energy storage device.
 9. The internal combustionengine of claim 8, wherein the charging system includes an alternatorconfigured to produce electricity.
 10. The internal combustion engine ofclaim 8, wherein the charging system produces electricity by receivingwaste electricity.
 11. The internal combustion engine of claim 1,wherein the electric motor turns off automatically in response to theengine reaching a threshold speed.
 12. The internal combustion engine ofclaim 1, wherein the electric motor turns off automatically in responseto a user removing a start input.
 13. The internal combustion engine ofclaim 1, wherein the electric motor turns off automatically after a setperiod of cranking time.